FIG. 1 is a functional block diagram depicting a conventional computer system providing operation voltage to a CPU. The computer system comprises a power supply 12, a PWM controller (pulse-width-modulation controller) 14, and a CPU 16 from which a VID (voltage identification) signal is outputted to the PWM controller 14, where the value of the VID signal is proportional to the load of the CPU 16. Because the power supply 12 and the PWM controller 14 must always provide enough power to the CPU, the PWM controller 14 must real-time modulates the operation voltage to the CPU 16 based on the real load of the CPU 16. That is, if the CPU 16 is operated in a relative-heavy load, the VID signal transmitted to the PWM controller 14 from the CPU 16 is accordingly relative large, so as the PWM controller 14 can modulate and output a relative-large operation voltage to the CPU 16 based on the relative-large VID signal. Similarly, if the CPU is operated in a relative-light load, the VID signal transmitted to the PWM controller 14 from the CPU 16 is accordingly relative small, so as the PWM controller 14 can modulate and output a relative-small operation voltage to the CPU 16 based on the relative-small VID signal.
The operation frequency of the CPU is also needed to be modulated according to the real load of the CPU, in other words, the operation frequency is needed to be increased if the load of the CPU is relative high, and, the operation frequency is needed to be decreased if the load of the CPU is relative low, where the operation frequency of the CPU is up to the HFM (highest-frequency mode) if the CPU is operated at a heaviest load; the operation frequency of the CPU is down to the LFM (lowest-frequency mode) if the CPU is operated at a lightest load.
However, the CPU is not necessarily restricted to operate between the HFM and the LFM. To get a better performance, the operation frequency of the CPU can be increased to higher than the HFM (for example, 10% or 20% higher than HFM), where the increasing of the operation frequency higher than the HFM is named overclocking. On the other hand, to get a better power saving, the operation frequency of the CPU can be decreased to lower than the LFM (for example, 10% or 20% lower than LFM), where the decreasing of the operation frequency lower than the LFM is named underclocking.
According to the specification of CPU, the operation voltage of the CPU must be increased first before the execution of the overclocking, where the increasing of the operation voltage can be named over-voltage. Similarly, the operation voltage of the CPU must be decreased first before the execution of the underclocking, where the decreasing of the operation voltage can be named under-voltage.
FIG. 2 is a functional block diagram depicting a conventional computer system capable of executing overclocking, underclocking, over-voltage, and under-voltage to a CPU. The computer system comprises a power supply 22, a PWM controller 24, a CPU 26, a control unit 28, a BIOS (basic-input-output-system) 30, a frequency generator 32, and an application program 34. The operation voltage can be increased via the BIOS 30. First, before the computer system entering to the operation system (OS), user can select a relative-high operation voltage from several operation voltages provided by a SETUP menu of the BIOS 30. After the relative-high operation voltage is selected, BIOS 30 then controls the control unit 28 to inform the PWM controller 24 to get ready to provide the selected relative-high operation voltage to the CPU 26. After the computer system entering to the operation system (OS), the selected relative-high operation voltage is then provided to the CPU 26, so as the over-voltage is done. After the over-voltage is done, user can execute the overclocking via the application program 32. First, user can select (or key-in) a relative-high operation frequency via the application program 34. After the relative-high operation frequency is selected (or key-in), the application program 34 then controls the BIOS 30 to inform the frequency generator 32 to generate the selected (or key-in) operation frequency (CLKCPU) and then provide to the CPU 26, so as the overclocking is done.
Similarly, the operation voltage of the CPU must be decreased first before the execution of the underclocking. The under-voltage and underclocking can be done via the above-described procedures, so as no unnecessary detail descriptions are given here.
However, once the operation voltage is modulated and computer system is entered to the operation system (OS), the operation voltage cannot be modulated again unless user reboots the computer system to make the computer system enter to the operation system (OS) again. Because the operation voltage cannot be real-time modulated according to the load of CPU, the power waste may be happened if the operation voltage is modulated to relative high but actually the relative-high operation voltage is not necessary in the computer system. Similarly, the poor performance may be happened if the operation voltage is modulated to relative low but actually the relative-low operation voltage is not enough to the computer system.